Traction assembly for a vehicle

ABSTRACT

This invention relates to a traction assembly for a vehicle which uses an endless traction band and a plurality of wheels for propulsion. The traction assembly pivots around a pivot point located under the traction axle of the vehicle. This pivot point is preferably longitudinally displaced in relation to such axle.

FIELD OF THE INVENTION

This invention relates to a traction assembly for a vehicle. Moreparticularly, the present invention relates to traction assemblies withlower and longitudinally displaced pivoting points.

BACKGROUND OF THE INVENTION

The type of surfaces over which a vehicle is ridden significantlyaffects its capacity and efficiency.

While the riding behavior is one of the most important aspects involvedin the concept of a vehicle, the ability to allow interchangeability ofparts or to retrofit new components on existing vehicles greatlysatisfies the owner of vehicles and represents an interesting marketsource for vendors of specialized parts destined to vehicles such assnowmobiles, motorcycles, all terrain vehicles (ATVs), tractors, trucks,etc.

Specialized parts for those vehicles include kits which may develop thevehicle's capacity to accomplish other functions, to extend its durationof use throughout the seasons or to allow the use of the vehicle underdifferent riding conditions.

For instance, different riding kits are sometimes installed to replacethe wheels of existing vehicles. In principle, the kits should minimizethe need to change existing components, must be able to fit on thevehicle without interference and should try to minimize any negativechange to the overall riding behavior of the vehicle and comfort of thedriver.

However, since most vehicles are initially designed for a typical use ona specific ground surface, some vehicle parameters like steering, weightdistribution or general stability may be affected by different vehicleuses combined with other components such as different riding kits. Forexample, a better riding behavior on snow usually requires less weightapplied to ski assemblies (usually located at the forward portion of thevehicle) than for a regular vehicle riding on another ground surface.

Numerous traction kits have been proposed throughout the years. In“Wheel Mount Track Conversion Assembly” (U.S. Pat. No. 5,607,210 issuedon Mar. 4, 1997), Brazier proposes a traction kits to replace the wheelsof wheeled vehicles. His system further comprises an anti-torque systemthat prevents the kit from contacting the vehicle. Though it can beeasily mounted on a wheeled vehicle, the system of Brazier does notinclude particular means to allow a better weight distribution or abetter maneuverability of the kit equipped vehicle. Moreover, thetraction kit of Brazier can only pivot around the axle axis.

In “Conversion System for All Terrain Vehicles” (U.S. Pat. No. 6,095,275issued on Aug. 1, 2000), Shaw proposes an ATV equipped with conversionkits such as ski assemblies and traction assemblies to replace existingwheels. Although adapting to the existing power system, the conversionsystem does not provide adjustability means for the weight distributionof the vehicle, such that the ATV's weight is dispersed to the groundsurface through the traction and ski assemblies. Also, as for Brazier,the traction kit of Shaw can only pivot around the axis of the axle.

The problem with these particular arrangements is that in order tofollow the bumps and depressions of the terrain over which the vehicleis ridden, the traction kit needs to pivot around the axis of the axle,which implies unnecessary large movements of the traction kit. Theselarge movements are translated into an uncomfortable ride for the user.Furthermore, these traction kits generally need means to prevent anycontact between the traction assembly and the body of the vehicle. Thesemeans generally add to the weight and cost of the assembly.

There is therefore a need for a traction assembly which improves ridingcondition when traction assemblies are used to replace existing wheelson vehicles.

OBJECTS OF THE INVENTION

Accordingly, an object of the present invention is to provide a tractionassembly for a vehicle which uses an endless traction band.

Another object of the present invention is to provide a tractionassembly which is compact and easily retrofitted on a vehicle.

Another object of the present invention is to provide a tractionassembly which can be easily installed either in the front or in theback of a vehicle or both.

Other and further objects and advantages of the present invention willbe obvious upon an understanding of the illustrative embodiments aboutto be described or will be indicated in the appended claims, and variousadvantages not referred to herein will occur to one skilled in the artupon employment of the invention in practice.

SUMMARY OF THE INVENTION

To attain these and other objects which will become more apparent as thedescription proceeds according to one aspect of the present invention,there is provided a traction assembly.

The object of the present invention involves a traction assembly thatcan preferably replace a wheel on vehicle. The traction assembly thusinvolves a vehicle with a frame and at least one traction axle.Preferably, the traction assembly can replace wheels on either side ofthe front portion and/or the rear portion of the vehicle.

More particularly, the traction assembly includes a sprocket wheel and alongitudinally extending traction band cooperating with such sprocketwheel. The sprocket wheel is preferably fixedly attached by means knownin the art to the traction axle (or the wheel hub) of the vehicle. Thetraction assembly also comprises a support structure, sometimes in theform of a slider bar, on which at least one but preferably two idlerwheels are pivotally mounted. These idlers wheels are preferably mountedat the extremities of the support structure. A plurality of road wheelscan also be pivotally mounted on either side the support structure toincrease the stability of the traction band.

In a first embodiment, the support structure (or slider bar) isconnected to the vehicle via a member which is non-drivingly mounted onthe sprocket wheel (or an extension thereof). More precisely, the firstend of the member is non-drivingly attached to the sprocket wheel or toa laterally extending structure axially extending from the sprocketwheel. This first end is preferably attached to the sprocket wheel or tothe laterally extending support with rollers or ball-bearings. Thesecond end is attached to a pivot point located under the traction axle,on the support structure (or slider bar) and preferably longitudinallydisplaced in relation to such traction axle. The member is preferablyrigid and can be adjustable.

To increase the adjustability of the pivot point, protuberancesextending toward or in vicinity of the sprocket wheel can be provided onthe support structure These protuberances include at least one andpreferably a plurality of pivot points to which the member can bepivotally attached.

To prevent any interference between the support structure and thevehicle and to support the traction kit, a preferably rigid linkconnects the member to the vehicle frame. The connections of this linkto the member and the frame are done preferably with ball-joint, bushingor rubber joint type connections. These connections allow for atri-dimensional adjustment. Using a shock absorber in place of the rigidlink could also be envisaged.

In another embodiment of the present invention, the support structure(or slider bar) is connected to the vehicle via a member which isfixedly mounted onto the suspension leg connected to the traction axle.As for the first embodiment, the second end of the member is pivotallyconnected to the support structure via a first pivot means located onthe support structure. This first pivot means is also located under theaxis of the sprocket wheel and axle. In this embodiment, there is noneed for another link connecting the member to the vehicle frame.Nevertheless, a shock absorber can preferably be pivotally connectedbetween the member and the support structure (or slider bar). This shockabsorber improves the riding quality of the vehicle.

Other aspects and many of the attendant advantages will be more readilyappreciated as the same becomes better understood by reference to thefollowing detailed description and considered in connection with theaccompanying drawings in which like reference symbols designated likeelements throughout the figures.

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an isometric view showing a vehicle including tractionassemblies according to one preferred embodiment of the invention.

FIG. 2 is a partial isometric view of the vehicle showing the tractionassembly of FIG. 1.

FIG. 3 is another partial isometric view of the vehicle showing thetraction assembly of FIG. 1.

FIG. 4 is a partial schematic elevation view of the vehicle showing thetraction assembly of FIG. 1.

FIG. 5 is a partial isometric view showing a vehicle including front andrear traction assemblies according to another preferred embodiment ofthe invention.

FIG. 6 is an exterior side view of another preferred embodiment of thetraction assembly of the present invention.

FIG. 7 is an interior side view of the traction assembly of FIG. 6.

FIG. 8 is an exterior perspective view of the traction assembly of FIG.6.

FIG. 9 is an interior perspective view of the traction assembly of FIG.6.

FIG. 10 is an exterior side view of a variant of the embodiment of FIG.6 without the spring.

FIG. 11 is an interior side view of the traction assembly of FIG. 10.

FIG. 12 is an exterior perspective view of the traction assembly of FIG.10.

FIG. 13 is an interior perspective view of the traction assembly of FIG.10.

FIG. 14 is an exterior side view of a variant of the embodiment of FIG.6 without the spring and the dampener.

FIG. 15 is an interior side view of the traction assembly of FIG. 14.

FIG. 16 is an exterior perspective view of the traction assembly of FIG.14.

FIG. 17 is an interior perspective view of the traction assembly of FIG.14.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to a traction assembly for a vehicle usingan endless traction band and a plurality of wheels for propulsion onirregular terrains.

The following description will be made according to embodiments of thepresent invention designed to be installed on ATVs and other similarvehicles. However, it is to be understood by the skilled addressee thatthe present invention can be adapted for any wheeled vehicles.Therefore, variants of the present invention adapted to be used ontrucks, tractors and other similar vehicles fall inside the scope of thepresent invention.

As seen in FIG. 1, the vehicle 24 is an ATV for which the regular wheels(not shown) are replaced with such traction assemblies 20 and skiassemblies 26. Such traction assemblies 20 can also replace the frontwheels of a vehicle as shown in FIG. 5. Other vehicles designed to rideon irregular, snowy, sandy, muddy or softer terrains can alsoincorporate the use of traction assembly 20. The traction assemblies 20can be mounted on each side of the front and rear portion of the vehicle24.

A first preferred embodiment of the traction assembly 20 is shown inmore details in FIG. 2. The traction assembly 20 includes a tractionband 28 which is preferably made of an endless elastomeric body 30,preferably reinforced by laterally extending stiffeners (not shown) thatmay or may not be completely embedded in the body 30. The body 30 of theband 28 has a ground-engaging outer side 32 comprising a selection ofdifferent lug profiles 34 separated from each other by a flat area 36.The inner side 38 usually has a plurality of guide lugs (not shown)which cooperate with a sprocket 40, idler wheels 42 and 44 and roadwheels 22 to ensure power transmission from the vehicle 24 to thetraction band 28 and stability.

FIG. 3 shows in more details how the sprocket 40 and wheels 42 and 44interact with each other and are installed to the structure 46 of thevehicle 24. On both sides of the structure 46 usually protrudes a shaft48 which includes a hub 50 providing support for the wheel/tireassemblies (not shown) of the vehicle 24. In the present invention, thesprocket 40 is preferably fixedly attached by any known method directlyto the hub 50 in place of wheel/tire assemblies (not shown).

A lateral support 52 extends from the sprocket 40 preferably along thecenter of rotation of the rotating components. The lateral support 52pivotally holds a member 54 which radially connects the sprocket 40 toidler 42, 44 and road wheels 22 (not shown) via a support structure orslider 56. The member 54 is connected to the slider 56 via a pivot 58and also includes a connection 57 where a link 60 connects the member 54to the chassis 62 or structure 46 of the vehicle 24. The pivot 58 islocated under the lateral support 52 and is preferably longitudinallydisplaced in relation with the lateral support 52 in order to change thecaster angle.

The link 60 is preferably a rod-like bar with roller ball joints,bushings or rubber joints 64 providing tri-dimensional adjustabilitywhile keeping the same predetermined length during the operation of thevehicle 24. However, the link 60 may include lengthwise adjustabilitymeans to suit the dimensions of different types of vehicles 24.

The slider 56 and the member 54 are pivotally connected by the pivot 58such that any significant relative motion between the two takes place asa rotation around the pivot 58. However, the rotation of the slider 56around pivot 58 can be limited by rubber stoppers attached on the frontand rear side of the member 54. These rubber stoppers help prevent thetraction assembly 20 to make contact with the vehicle 24. Other contactpreventing means could also be used without departing from the scope ofthe invention. The member 54 is mounted on the lateral support 52,preferably with rollers (not shown), such that it is not movably coupledto the rotating shaft 48 or sprocket 40 in operation.

Since the member 54 is free to rotate around the pivot 58, thepredetermined length of the link 60 restrains the relative movementbetween the shaft 48 (and thus sprocket 40) (to which the link 60 isconnected via the member 54 and the lateral support 52) and the slider56 (to which the link 60 is connected via the member 54 and pivot point58). Therefore, the interference risks between the sprocket 40 and theslider 56 are minimized.

The support structure or slider 56 consists of a structure whichsupports idler wheels 42 and 44 and a plurality of road wheels 22 andcooperates with the traction band 28. The slider 56 longitudinally orcircumferentially extends in such a way as to give form to the tractionband 28. The design of the slider 56 depends on the desired overallriding characteristics.

In the variant shown in FIGS. 1 to 4, the slider 56 preferably includesat least one protuberance 66 extending in the vicinity of or toward thesprocket 40. The protuberance 66 is generally located under the support52. The protuberance 66 supports the pivot 58 through mounting means(not shown). Also, as best depicted in FIG. 4, the protuberance 66 ispreferably longitudinally located toward the front of the vehicle.

Depending on the number of idler wheels 42, 44 and road wheels 22 beingsupported by the slider 56, side wheel supports 68, 70 (shown in FIG. 1)which are fixedly connected to the slider 56 offer a pivotal connectionto support the idler wheels 42, 44 and the road wheels 22.

Therefore, the traction assembly 20 comprises the traction band 28, thesprocket wheel 40, the laterally extending support 52, the member 54,the pivot 58, the protuberance 66, the link 60, the slider bar 56,preferably at least idler wheels 42 and 44 and preferably a plurality ofroad wheels 22. The interactions between those various components whilethe vehicle 24 is in operation are illustrated in more details in FIGS.1 and 4.

A second preferred embodiment is shown in FIGS. 6-9 (and also 10-13 and14-17). In this embodiment, the traction assembly 120 similarlycomprises a support structure or slider bar 156 which supports idlerswheels 142 and 144 pivotally mounted at both extremities and a pluralityof road wheels 122 pivotally mounted in-between. The support structure156 further comprises a pivot point 158, located under the axis of thesprocket wheel 140. Pivot point 158 is preferably longitudinallydisplaced in relation to the axis of the sprocket wheel 140 in order tochange the caster angle.

The sprocket wheel 140 is fixedly attached to the axle (not shown) orthe wheel hub (not shown) of the vehicle 24.

In this second embodiment, the support structure 156 is not connected tothe axle (not shown) or an extension thereof. Support structure 156 isinterconnected to the suspension leg 149 which is generally connected tothe axle in a known manner, with the help of member 154. The first endof member 154 is fixedly attached to the lower portion of the suspensionleg 149 using a bracket assembly 150. The second end of member 154 ispivotally mounted to the support structure 156 via pivot point 158. Theparticular configuration of bracket assembly 150 depends on theparticular configuration of the suspension leg lower portion. Therefore,different bracket assembly 150 should be necessary according to thedesign and shape of the suspension leg 149 used on different vehicles.

The skilled addressee will readily understand that the support structure156 is not directly connected to the sprocket wheel 140 as in the priorart. Thus, support structure 156 can only pivot around pivot point 158.If the vehicle 24 equipped with traction assemblies 120 is ridden overuneven terrain, the amplitude of the movements of the tractionassemblies 120 will be smaller, thus improving the riding quality if thevehicle.

To further improve the riding quality of vehicle 24 equipped withtraction assemblies 120, the traction assembly 120 can further comprisea second pivot point 164, located on support structure 156 andlongitudinally displaced in relation to the first pivot point 158. Inthe embodiment shown in FIGS. 6-17, the second pivot point 164 ispreferably located in front of the first pivot point 158. However, thesecond pivot point could be located behind the first pivot point. Athird pivot point 165 is located on the upper portion of the member 154.A shock absorber comprising a dampener 160 and a spring 162 is pivotallymounted between pivot points 164 and 165. The skilled addressee willnote that even if this second preferred embodiment preferably comprisesa shock absorber comprising a dampener 160 and a spring 162, the secondembodiment would nevertheless work without the spring 162 and evenwithout the spring 162 and the dampener 160 as shown in FIGS. 14 to 17.

When the vehicle is ridden and the traction assemblies 120 face a bump,the front portion of the traction assembly 120 facing the bump willrise, by pivoting around pivot point 158, in order to follow curvatureof the terrain. However, if the bump is abrupt, the rising movement ofthe traction assembly 120 can be sharp and thus uncomfortable for therider. The presence of the shock absorber 160 prevents sharp movementsby partially absorbing and dampening the movement.

The same principles apply when the front portion of the tractionassembly 120 faces a depression. The shock absorber 160 will prevent anysharp descending movements.

To improve the adjustability of the traction assembly 120, the supportstructure 156 could comprise a plurality of pivot points 158longitudinally displaced in relation to each other.

Also, with the use of an adjustable shock absorber 160, it would bepossible to artificially rise or lower the front portion of the tractionassembly 120 should it be needed.

Obviously, the skilled addressee will understand that a traction band(not shown), known in the art, is tensioned around the sprocket wheel140, the idlers wheels 142 and 144, the road wheels 122.

Although preferred embodiments of the invention have been described indetail herein and illustrated in the accompanying figures, it is to beunderstood that the invention is not limited to these preciseembodiments and that various changes and modifications may be effectedtherein without departing from the scope or spirit of the presentinvention.

1. A traction assembly for use on a vehicle having a frame, at least onetraction axle and at least one suspension leg coupled to said at leastone traction axle, said assembly comprising a sprocket wheel adapted tobe coupled to said axle, a longitudinally extending support structureand a traction band tensioned around and cooperating with said sprocketwheel and said support structure, said traction assembly furthercomprising a member having a first end adapted to be fixedly mounted tosaid at least one suspension leg and a second end pivotally mounted tosaid support structure at a first pivot point wherein said first pivotpoint is located under a rotation axis of said sprocket wheel wherebysaid support structure can pivot around said first pivot point.